Dieter Jaksch awarded with the 2018 Thomas Young Medal and Prize

for "his contributions to theoretical proposals enabling the study of non-equilibrium quantum many-body dynamics with unprecedented microscopic control in ultra-cold atoms, and establishing them as a quantum technologies platform".

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Jean-Marc Triscone awarded a honorary doctorate

by the Norwegian University of Science and Technology (NTNU)

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Publication Detail / Abstract

P. Seth, O. E. Peil, L. Pourovskii, M. Betzinger, C. Friedrich, O. Parcollet, S. Biermann, F. Aryasetiawan, A. Georges

Renormalization of effective interactions in a negative charge-transfer insulator

> Full text via publisher
We compute from first principles the effective interaction parameters appropriate for a low-energy description of the rare-earth nickelate LuNiO3 involving the partially occupied eg states only. The calculation uses the constrained random-phase approximation and reveals that the effective on-site Coulomb repulsion is strongly reduced by screening effects involving the oxygen-p and nickel-t2g states. The long-range component of the effective low-energy interaction is also found to be sizeable. As a result, the effective on-site interaction between parallel-spin electrons is reduced down to a small negative value. This validates effective low-energy theories of these materials proposed earlier. Electronic structure methods combined with dynamical mean-field theory are used to construct and solve an appropriate low-energy model and explore its phase diagram as a function of the on-site repulsion and Hund's coupling. For the calculated values of these effective interactions we find, in agreement with experiments, that LuNiO3 is a metal without disproportionation of the eg occupancy when considered in its orthorhombic structure, while the monoclinic phase is a disproportionated insulator.
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